Improvement in hot-air engines



s.H.R'oPBR. HOT AIR ENGINE.

PatentedJune9,186 3'. y

UNITED STATES PATENT OFFICE.

sYLvES'rEE H.1 .OPEE`,OE BOSTON, MASSACHUSETTS, ASSIGNOR TOQELMEE TOWNSEND, vOE SAME PLAGE. z

iMPaovEMl-:NT IN HOT-AIP. ENGINES.

Specification forming part of Letters Patent No. 38,866, dated June 9, 1863.

To all whom itfmay concern.:

Be it known that I, SYLVESTER H. ROPER, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain Improvements in Hot-Air Engines, of which the followingis a full, clear, and exact description, reference being had to the accompanying drawings, making part of this specification, in which- A Figurel is a perspective view, Fig. 2, aplan 5 Fig. 3, a vertical section upon the line x :v of Fig. 2 5 Fig. 4, an underneath view of the hollow piston V, the bottom plate being removed to show the deiiectingplate within. The body or exterior casing, A, rests upon the base B. Y

The re-box D is made of a single casting,

`Gr, thus avoiding all jointsat which leakages might occur, and to protect the iron from the intense heat of the fire the box is surrounded upon the inside with fire-brick or soapstone, E. The upper plate of the casting Gr is also protected by a slab or plate of soapstone or fire-brick, F, which eftectually screens it from the direct'action of the fire.

The cylinder is divided into a lower portion, H, and an upper portion, R. The lower portion is formed of a single casting, H2, and is inserted at the top of the casing A, the flange h, of the casting resting upon the top i2 of the casing A. The space g2, between the casting and the casing', is then filled with calcined plaster or some equivalent non-conducting substance. This may be done by inverting the casting and placing the casing over it. The lower casting, G, is then placed with its upper plate upon the lower plate, H2, ot' the cylinder, and the space 5, between the lower casting andthe casing,is also filled with pla-ster. The entire furnace, as well as that portion of the cylinder which is exposed to the heat, is thus surrounded. ,by a non-conducting substance, by which great economy of heat is effected.

The fuel is fed to the furnace in the following manner: I is a cylinder, having a tightfitting cover, K, which is secured by clamps or screws in any well-known manner to its seat. The cover shown in Fig. 1 is curved,

Y but in practice it is preferable to make them dat, as theyare more easily fitted and made tight than' when curved. Within this cylinder is a piston, L, having a rod a, which passes through a stuffing-box in the end of the cylinder, andis furnishedwith a handle by which the piston may be manipulated. From the top of the cylinder rises a narrow chamber, M in which slides a disk or plate valve, N, a'portion of which is seen in Fig. 1, the cylinder and chamber being broken away to show it. The valve N is manipulated by'means of a rod, bz, rising fromt he plate, which passes through a stuiiingbox, c, in the top of the chamber M. When the valve is down, as represented in Fig. 1, it cuts oif'the communication between the furnace and the cylinder. When the iie is to be replenished, the cover K is removed, yand. the piston L is drawn back. The coal is then put into the-cylinder. The cover is replaced, t'ne valve N is raised, and the coal is forced, into the furnace by meansof the rod. d.

O is a tight-fitting door, through which the furnace may be fed by. hand, and P a similar door to the ash-pit. The heated air from-the furnace is admitted tothe cylinderthrough' a valve-chest, S, and valve f, and vis exhausted through the valve y and pipe h into a chimney or other suitable conduit, there being a passage, d, iitted air-tight to the furnace and the valve-chest, and a corresponding opening in the re-brick lining. The passage from thel valve-chest to the cylinder is also fitted airtight at each end. The valve-rods tv and Lk, which pass through stui'iing-boxes l?l la?, 'are y, actuated in a well-known manner'by tap'pets upon a rock-shaft, l, which is set in motionby an eccentric or by a crank upon theshaft G2," one end of therod T being connectedwith the crankand the other with the arm n upon the rock-shaft.

The most serious difficulty thus far Aencountered in the construction and operation of hotair engines arises from the great heat to which the cylinder and piston are exposed, and the consequentdestruction ofthe oil usf-fl for lubricating them. To remedy this inconvenience, I adopt the following construction g The upper portion, R, of the cylinder, or that portion which comes in contact with the piston, is isolated from the lower portion, which receives the heated air, a cylinder, U, of thin sheet metal being interposed between them. This cylinder is secured between the flanges h2 and g, and the whole arevheld together by the bolts p. The cylinder U, being made as' thin as may be and stand the pressure within, and being constantly refrigerated by radiation and by exposure to the atmosphere, transmits only a triing amount o f heat to the cylinder R, which thus remains constantly so cool as not to destroy the oil used to lubricate it. The piston V is hollow, and has an open cylinder t, projecting above its upper plate, r, a ring of packing, s, being secured to the upper edge of the cylinder by a metallic ring, n2, and screws o2. Beneath the piston V is the prolongation W, which fits loosely in the cylinder and descends on the downstroke to near the bottom 'of the chamber H.

For the purpose of more completely cooling the piston, the air for driving the engine is all passed through-it on its way to the firebox hy the following means: Above the cylinder, and secured to the top thereof by screw bolts or otherwise, is the air-pump A2, in which works the piston ar, -the rod z ot' which is hollow and is attached to the upper plate, r, of the piston, V. The piston .r is hollow, and has two flap-valves, l and 2,0peninginward. The upper head of the air-puin p has a valve, 3, opening doWnward,-and the lower head a valve, 4, opening upward. By means ofthe hollow rod z the cavity in the pistonV is connected with the eavity in the piston w. Apipe, Y,extending up from the cavity in the piston V, slides airtight Within a stationary pipe, Z, rising from the base a2 of the airpump. The pipe Z is bent down and enters a passage, m2, passing down within the casting A. From this passage there are two pipes, d2 and f2, leading the one to the re-box and the other to the ashpit beneath the grate-bars G.

4The operation of this part of the engine is as follows: As the pistonV rises, carrying -with it the air-pump piston a', the valves 4 and 1 are operated, and the valves 2 and 3 are closed, the air above the piston a: passing through the hollow rod z to the interior of the piston V, up through the pipe Y, down through the pipe Z and passage :r2 to the firebox. At the same time that this is taking i place, the valve 4 in the bottom of the airpump is opened, and air enters beneath the piston x. On the descent of the pistons V and av, the valves2 and 3 are opened and 1 and et are closed, andthe air is forced through the'chalnber in the piston, V, as before to the fire-box, and thus a constant current of air is passed through the piston,by which any heat that may be conducted to it through the prolongation W is carried oft', and it is kept so cool that the oil used for lubricating the piston is not destroyed or changed. The air is made to circulate more perfectly through the piston by the deflecting-plate C2, Figs. 3 and 4.

In order to regulate the force with which the fire is urged to accord with the work upon the en gine, the pipes d2 and f2, one of which enters the fire-box above the fire and the other the ashpit beneath the grate-bars, are furnished with valves 5 and 6, the rods 7 and 8 of which pass out through stuffing-boxes 9 and 10, and are manipulated by hand. When the upper valve is opened and the lower one closed, the air is all thrown above the fire, and, in proportion as the lower valve is opened, more air is admitted beneath the grate-bars and is passed through the'iire, by which the re is urged to a greater intensity. The working- -piston is connected, by means of rods O2, with the up-and-down beam D2, that vihrates upon a standard, E2, rising from the main cylinder, and from which the power is communicated by the connecting-rod F2 to the driving-shaft G2, whichcarries the ily-wheel H2.

For the purpose of regulating the speed of the engine, the following device is employed:

One of the legs, i2, Fig. 2, which supports the t air-pump, has a passage through it, Fig. 2, which communicates with the interior of the airpump and with apipe, k2, near .to the outer end of which are one or more openings through which air from the pump is allowed to escape when the openings are notv covered by the. inclosing-sleeve m2. This sleeve is operated by the governor-balls, which slide-upon the arms '02, projecting from another sleeve, q2, which is prevented from moving longitudinally on the pipe k3 by collars 11 and 12. This sleeve, togetherwith the sleeve m2, is revolved upon the pipe k3 by a band or strap from the pulley m on the main shaft, running upon the pulley b3, and thus, when the rate of motion of the en'- gine exceeds the desired limit, the holes in the pipe k2 will be uncovered, and air will be permitted to escape, thus modifying the press ure within the fire-box and cylinder.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. Lining'the fire-box with tire-brick or their equivalent upon all sides,except the bottom, as set forth.

2. The parts or pieces ofthe fire-box G and H2, in combination with the exterior casing, A, the space between vthem being illed with` plaster or its equivalent, for the purpose specified.

3. The induction-pipes d2 72, arranged and operating as described, in combination with the pipe or passage which brings-the air from the air-pump to the furnace, for the purpose of regulating the intensity of the fire, as set forth. i

S. H. ROPER. Witnesses:

SAM. GcoPEn, P. E. TESCHEMACHER. 

